Cooling fluid streams by air instead of water is an inherently more environmentally friendly option. Indeed, restriction on water consumption for industrial use, especially to condense waste steam in power plants, has emerged as a growing worldwide problem. Driven by increasing scarcity of water, power plant designers have been turning to air-cooled condensers, such as that which is shown in FIG. 1 in lieu of the conventional water-cooled condensers. Existing air-cooled condensers consist of inclined tube bundles organized in “cells” wherein the turbine exhaust steam flows inside the tubes and is condensed by the flow of cooling air in a cross flow mode delivered by axial fans located underneath. A typical air-cooled condenser unit 10 is shown in FIG. 1 and comprises a plurality of inclined tube bundles 11 arranged in an A-frame structure. A main stem duct 12 delivers steam from a turbine into a distribution manifold 13. The steam passes through the distribution manifold 13 and into the risers 14, where it then flows into the distribution headers 15. The distribution headers 15 deliver the steam into the inclined tube bundles 11 where thermal energy from the steam is transferred to air flowing on the outside of the inclined tube bundles 11. The tube bundles 11 are positioned atop a fan deck platform 16 that comprises a plurality fans 17 for forcing cooling air to flow adjacent and through the inclined tube bundles 11. The fan deck platform may be situated atop a frame 18 so that cooling air can be drawn upward. A windwall structure 19 may also be provided.
Prior art air-cooled condenser configurations have several disadvantages that have limited its wide application, such as: (1) high capital cost; (2) large land area requirement; (3) significant site construction effort; and (4) contamination of condensate (deleterious iron carry over) by corrosion of the carbon steel tubing and associated reduction in the service life of the system.
Thus, a need for an improved air-cooled heat exchanger, and improved finned tubes for use with the same, exists.